The Evidence on E-cigarettes: Evaluating What We Have and Identifying What We Need

The Evidence on E-cigarettes: Evaluating What We Have and Identifying What We Need Ken Warner University of Michigan School of Public Health U.S. E-cigarette Summit, Washington, DC, May 8, 2017

Conflicts Disclosures I have no professional conflicts of interest. I am conflicted about being in this meeting on a beautiful day for golfing in northern Michigan. Funding sources I have no visible means of support for this presentation or anything else I do.

Areas of difference between e-cigarette enthusiasts & skeptics Issue Enthusiasts Skeptics Degree of risk reduction >95% Unknown; likely much <95% Primary articulated concern Maximizing adults quitting smoking Minimizing risks to kids Nature/magnitude of risks to kids Minimal; e-cigarettes may substitute for smoking Feared substantial: gateway to smoking; renormalization; effects on developing brain Impact on adult quitting Potential to help millions May reduce quitting Precautionary principle Smoking toll is an emergency; requires support of novel products Long-term nicotine addiction Acceptable if eliminates smoking Not acceptable Cigarette and e-cig companies Open to working with them Not to be trusted First do no harm ; need to first prove (relative) safety & effectiveness Free market Strongly support Worry about Wild West Scientific studies Support/discredit Support/discredit Product regulation Information dissemination Policies, e.g., vaping where smoking prohibited; flavors; taxation Favor limited regulation that won t disrupt innovation Emphasize harm reduction potential for adult smokers Oppose location restrictions; support flavors (to assist in adult quitting); no/low tax Support strong regulation to ensure safety/effectiveness Emphasize risks for kids and risks of dual use for adults Support location restrictions; oppose flavors (to reduce attractiveness to kids); tax

Prospective studies of use of e-cigarettes and subsequent smoking Huh and Leventhal, Am J Prev Med, 2016 Barrington-Trimis et al., Pediatrics, 2016 Leventhal et al., JAMA, 2015 Leventhal et al., JAMA, 2016 Miech et al., Tob Control, 2017 Primack et al., JAMA Ped, 2015 Wills et al., Tob Control, 2016 Wills et al., Psychol Addict Behav, 2016 Wills et al., Tob Control, 2017 Spindle et al., Addictive Behaviors, 2017

Limitations of prospective studies 1. How control adequately for fact that vapers are different from non-vapers? 2. Control for use of other psychoactive substances 3. What happens when controls do capture major differences between vapers and non-vapers? 4. Extent of cigarette use at follow-up 5. Small size of studies

30-day product use by US high school students, NYTS, 2011-2015 Singh et al., MMWR, 2016

The LAST TIME you used an electronic vaporizer such as an e-cigarette, what was in the mist you inhaled? 12 th graders in MTF, by smoking status, 2015 (%) Smoking E-cig mist Never Once/twice Occasionally Regularly in the past Regularly at present Nicotine 11.3 17.9 34.0 38.5 63.7 Marijuana or hash oil 3.4 6.4 9.4 11.4 5.9 Just flavoring 78.4 68.2 48.6 47.6 25.5 Other 0.4 1.3 0.6 0 1.5 Don't know 6.5 6.2 7.3 2.5 3.4

12 th graders e-cigarette use in past 30 days by ever-smoking status, 2014 Ever-smoking status Used e-cigarettes (%) Never 6.5 Once or twice 25.8 Occasionally, not regularly 47.8 Regularly in past 46.8 Regularly now 57.3 Warner, AJPM, 2016 (MTF data)

Estimated increased number of additional long-term quitters associated with e-cigarette use in England 16,000-22,000 by one indirect estimation method; 22,000-28,000 by another (in 2014) West et al., Addiction, 2016 18,000 using ARIMAX modelling approach (in 2015) Beard et al., BMJ, 2016

Assumptions for simulation 1. E-cigarette use leads never-smoking kids to try smoking 2. Assume a very high estimate of how much Results in 4.2% increase in 18 year-old smokers Applies to every cohort of 18 year-olds through 2050! 3. Assume e-cigarettes increase net smoking cessation rate by 5% 4. All smokers subject to age-specific quit probability (total 4.2%) 5. All smokers, former smokers, and never smokers subject to age- and smoking-status-specific death rates 6. Track numbers of smokers and life-years lost for (youthful) vaping-induced smokers and gained for (adult) vaping-induced quitters through 2050

Cumulative life-years saved or lost by scenario, 2014-2050 Year Scenario 1: Initiation rate 4.2% Change in life-years Scenario 2: Quit rate 5% Scenario 3: Both initiation and quit rates 2014 0 1,649 1,649 2020 0 39,157 39,157 2030 293 269,364 269,074 2040 14,980 741,517 726,727 2050 88,413 1,332,905 1,245,639

Models examining impacts of e-cigarettes or generic reduced-risk products Bachand and Sulsky, Regulatory Toxicology and Pharmacology, 2013 Kalkhoran and Glantz, JAMA Int Med, 2015 Vugrin et al., PLOS ONE, 2015 Levy et al., NTR, 2016 Cherng et al., Epid, 2016

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